filter reactor, is used to reduce the amplitude of the ripples in the DC current of the rectifier circuit, and can form the circuit resonant to a certain frequency together with capacitor to eliminate the voltage or current of a ceritain harmonic in the power circuit. It connects in series with with the shunt capacitor to form the resonant circuit to filter out the designated high harmonics. The branch circuit of the filter is capacitive to the fundamental frequency, and can meet the requirements of reactive compensation.